Field of the Invention
The present invention relates to an inorganic polarizing plate, a method of manufacturing the inorganic polarizing plate, and an optical instrument.
Related Art
A polarizing plate is an optical element that absorbs polarized light in an absorption-axis direction and transmits polarized light in a transmission-axis direction perpendicular to the absorption-axis direction. In recent years, instead of organic polarizing plates, wire grid type inorganic polarizing plates have begun to be adopted in optical instruments such as liquid crystal projectors which require heat resistance.
Up to now, as the wire grid type inorganic polarizing plate, inorganic polarizing plates having various structures have been proposed.
For example, Patent Document 1 discloses an inorganic polarizing plate having a structure as illustrated in FIG. 13. The inorganic polarizing plate 50 illustrated in FIG. 13 includes a transparent substrate 51 and grid-shaped protrusions 52 arranged on the transparent substrate 51 at a pitch shorter than a wavelength of light in a use band, and the grid-shaped protrusion 52 includes a reflection layer 521, a dielectric layer 522, and an absorption layer 523 in this order from the transparent substrate 51 side. For the absorption layer 523, for example, a metal-containing semiconductor such as FeSi is used.
In addition, Patent Document 2 also discloses an inorganic polarizing plate including a transparent substrate, a grid (reflection layer) arranged on the transparent substrate at a pitch shorter than a wavelength of light in a use band, and a low reflection member laminated on the grid. For the low reflection member, for example, a mixture of a metal and a dielectric material is used.
Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2015-34959
Patent Document 2: Japanese Unexamined Patent Application, Publication No. 2008-46637